[clang] [llvm] [Clang][AArch64] Add customisable immediate range checking to NEON (PR #100278)

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@@ -1959,9 +2064,12 @@ multiclass VCMLA_ROTS<string type, string lanety, string laneqty> {
 
     let isLaneQ = 1 in  {
       // vcmla{ROT}_laneq
+      // ACLE specifies that the fp16 vcmla_#ROT_laneq variant has an immedaite range of 0 <= lane <= 1.
+      // fp16 is the only variant for which these two differ.
+      // https://developer.arm.com/documentation/ihi0073/latest/ 
+      defvar getlanety = !if(!eq(type, "h"), lanety, laneqty);
       def : SOpInst<"vcmla" # ROT # "_laneq", "...QI", type,  Op<(call "vcmla" # ROT, $p0, $p1,
-              (bitcast $p0, (dup_typed lanety, (call "vget_lane", (bitcast laneqty, $p2), $p3))))>>;
-
+                (bitcast $p0, (dup_typed lanety, (call "vget_lane", (bitcast getlanety, $p2), $p3))))>>;
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Lukacma wrote:

I am not sure I follow what you trying to say there. I think, it might be because your link to FCMLA is for the old spec and there may be some differences in instruction spec compared to the latest one. But if you look at the most recent spec for this [instruction](https://developer.arm.com/documentation/ddi0602/2024-06/SVE-Instructions/FCMLA--indexed---Floating-point-complex-multiply-add-by-indexed-values-with-rotate-), it says quite clearly that immediate range for half-precision variant is from 0 to 3

https://github.com/llvm/llvm-project/pull/100278